Messages in this thread | | | Date | Mon, 29 Dec 2003 11:32:00 -0800 | From | "Martin J. Bligh" <> | Subject | Re: [Lse-tech] Re: [RFC][PATCH] 2.6.0-test11 sched_clock() broken for "drifty ITC" |
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>> Could you please finalise it, cook up the ia64 and numaq implementations >> and send it over? > > I believe the "ia64 implementation" stands as-is, since it uses the low- > overhead ITC. > > I'm not familiar with NUMAQ issues, but perhaps this timer_tsc.c change > would be appropriate? It allows i386 CONFIG_NUMA platforms to potentially > use the TSC for sched_clock() timings, given that sched_clock() no longer > requires that the TSC be synchronized across all CPUs. It does, however, > require that "use_tsc" be properly initialized for i386 CONFIG_NUMA. Is > that a valid assumption?
I don't think there's anything special about use_tsc for NUMA-Q - it's set to 1 AFAICS. I had a patch to force notsc on about 6 months or so ago, but it made the machine crash hard in strange ways I never bothered debugging.
Is there any harm in dropping the first part of your patch, ie.
> diff -X /home/hawkes/Patches/ignore.dirs -Naur linux-2.6.0/arch/i386/kernel/timers/timer_tsc.c linux-2.6.0-schedclock2/arch/i386/kernel/timers/timer_tsc.c > --- linux-2.6.0/arch/i386/kernel/timers/timer_tsc.c Mon Nov 24 12:18:20 2003 > +++ linux-2.6.0-schedclock2/arch/i386/kernel/timers/timer_tsc.c Sat Dec 13 11:33:04 2003 > @@ -138,9 +138,7 @@ > * In the NUMA case we dont use the TSC as they are not > * synchronized across all CPUs. > */ > -#ifndef CONFIG_NUMA > if (!use_tsc) > -#endif > return (unsigned long long)jiffies * (1000000000 / HZ); > > /* Read the Time Stamp Counter */
and leaving the rest of it? the CONFIG_NUMA affects both NUMA-Q and Summit, BTW, which uses the cyclone timer, so it gets even more complex ;-)
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